When you talk of the piston in an engine ,Do you speak of the piston or the piston rod assembly?
Its the piston.Not the rod

There you go trying to use logic again.
That's the whole point of this thread. You can't use logic when trying to interpret anything the ATF does.

In the two photo's below (ignore the fact that one has the bolt in it)
According to the ATF, one is a pic of a carrier and a piston, two countable parts. The other is a carrier and that's it, no piston, (not even a op rod) and is only one countable part.

There you go trying to use logic again.
That's the whole point of this thread. You can't use logic when trying to interpret anything the ATF does.

In the two photo's below (ignore the fact that one has the bolt in it)
According to the ATF, one is a pic of a carrier and a piston, two countable parts. The other is a carrier and that's it, no piston, (not even a op rod) and is only one countable part.

Where's the logic in that?

You are correct ,there is none.
Where did you get "According to the ATF, one is a pic of a carrier and a piston, two countable parts. The other is a carrier and that's it, no piston, (not even a op rod) and is only one countable part." Did this come from the BATFE website,a Liaison or ....?Link please.
We know the BATFE critters lack critical thinking skills ,and worse yet depending on the time of day you can get 6 answers from 4 different people at one time.As always get it in writing.
I think however that we will find that it is soley the piston.I am quite sure that Tony R. and the others that are making this part have done the leg work for us and got the correct answers and paper work to back it up.
I look forward to seeing the link .

Where did you get "According to the ATF, one is a pic of a carrier and a piston, two countable parts. The other is a carrier and that's it, no piston, (not even a op rod) and is only one countable part." Did this come from the BATFE website,a Liaison or ....?Link please.
I look forward to seeing the link .

Are you asking how we know that this is considered the gas piston and a 922r countable part in a AK?
Are You kidding Me?

It is not just one person who makes these decisions. First one person at the Technology Branch made up a list of guns and their parts counts. Then as folks wrote in to ask about other guns, whoever got assigned the task of answering the letter made the decision. Throw in political pressure on top of all that and you get the results that we see.